Al-zn-cu alloy and manufacturing method thereof

Abstract

The present invention relates to an Al—Zn—Cu alloy comprising: 18 to 50 parts by weight of zinc; 0.05 to 5 parts by weight of copper; and the rest being aluminum, based on the total weight of the alloy, wherein a tensile strength is 230 to 450 MPa and an elongation is 2.75 to 10% in the cast state. According to the present invention, it is possible to provide an Al—Zn—Cu alloy having improved casting property, strength and elongation at the same time.

What is claimed is: 
     
         1 . An Al—Zn—Cu alloy comprising:
 18 to 50 parts by weight of zinc; 
 0.05 to 5 parts by weight of copper; and 
 the rest being aluminum, based on the total weight of the alloy, 
 wherein the Al—Zn—Cu alloy has at least one of the following features: 
 1) a tensile strength of 230 to 450 MPa and an elongation of 2.75 to 10% in the cast state; 
 2) 2θ of a Zn(0002) plane of a lattice constant in the X-ray diffraction of 36.3 to 36.9; and 
 3) 2θ of a Zn(1000) plane of the lattice constant in the X-ray diffraction of 38.7 to 38.9. 
 
     
     
         2 . The Al—Zn—Cu alloy of  claim 1 , wherein the tensile strength in the cast state is 310 to 450 Mpa. 
     
     
         3 . The Al—Zn—Cu alloy of  claim 1 , wherein the elongation in the cast state is 4 to 10%. 
     
     
         4 . The Al—Zn—Cu alloy of  claim 1 , wherein a conductivity is 37% IACS (International Annealed Copper Standard) or more. 
     
     
         5 . The Al—Zn—Cu alloy of  claim 1 , wherein at least one of the diameter and the length of a Zn phase in an Al matrix is 10 to 100 nm. 
     
     
         6 . The Al—Zn—Cu alloy of  claim 1 , further comprising at least one of more than 0 to less than 1 part by weight of magnesium and more than 0 to less than 0.5 parts by weight of silicon, based on the total weight of the alloy. 
     
     
         7 . An Al—Zn—Cu alloy heat-treated with the Al—Zn—Cu alloy of  claim 1  to have a tensile strength of 330 to 600 Mpa. 
     
     
         8 . The Al—Zn—Cu alloy of  claim 7 , wherein the Al—Zn—Cu alloy has elongation of 4 to 12%. 
     
     
         9 . The Al—Zn—Cu alloy of  claim 7 , wherein the heat-treatment is performed at a temperature of 150 to 500° C. 
     
     
         10 . A method for manufacturing an Al—Zn—Cu alloy of  claim 1  comprising:
 preparing an alloy molten comprising:
 18 to 50 parts by weight of zinc; 
 0.05 to 5 parts by weight of copper; and 
 the rest being aluminum, based on the total weight of the alloy; and 
 
 casting by filling the alloy molten into a metallic mold or a sand mold. 
 
     
     
         11 . The method of  claim 10 , wherein the step for preparing an alloy molten is performed at 650 to 750° C. and comprises degassing after the alloy is completely melted. 
     
     
         12 . The method of  claim 10 , wherein tensile strength of the Al—Zn—Cu alloy is 230 to 450 MPa and elongation is 2.75 to 10% in the cast state. 
     
     
         13 . The method of  claim 10 , wherein the Al—Zn—Cu alloy has 2θ of a Zn(0002) plane of the lattice constant in the X-ray diffraction of 36.3 to 36.9. 
     
     
         14 . The method of  claim 10 , wherein the Al—Zn—Cu alloy has 2θ of a Zn(1000) plane of the lattice constant in the X-ray diffraction of 38.7 to 38.9. 
     
     
         15 . The method of  claim 10 , wherein the Al—Zn—Cu alloy has at least one of the diameter and the length of the Zn phase in the Al matrix of 10 to 100 nm. 
     
     
         16 . The method of  claim 10 , further comprising forming a solid solution by heat-treating the Al—Zn—Cu alloy at a temperature of 150 to 500 IC. 
     
     
         17 . The method of  claim 16 , wherein the heat-treatment is performed for 30 minutes or more. 
     
     
         18 . A cast product manufactured from the alloy of  claim 1 . 
     
     
         19 . A machined aluminum alloy product manufactured from the alloy of  claim 1 .